This invention relates to an improved locking device adapted to maintain two electric cords in contact. More particularly, the invention relates to electric cord locking means designed to prevent inadvertent separation of a plug of an electric cord connected to a socket of an extension cord thus assuring continuous electric connection between the two conductor cords.
With considerable expansion in the use of power tools or movable house appliances the user frequently faces a situation where the electric cord originally connected to a power tool or appliance is not sufficiently long for the tool to reach a desired point of use thus necessitating its connection to a conventional extension cord so that the motor-driven device could be operated at a substantial distance from the nearest electric outlet. However, in cases where it is necessary to move the power tool or appliance during the use thereof, the pull exerted on the joined cords often causes the male plug and the female socket to separate thus interrupting the power supply to the tool or appliance which is annoying to the operator and time consuming for connecting the two electrical cords again.
Various types of locking devices for securing electric cords and extension cords together have been described in the patent literature. For example, U.S. Pat. No. 3,999,828 describes a non-adjustable cord connector having two ends of configuration connected by straps and a wedge which is molded with the body of the connector and connected by a strap to one end thereof. U.S. Pat. No. 3,609,638 covers an extension cord clamp assembly which is formed of a grooved rod and a pair of spring-biased clamps mounted thereon. U.S. Pat. No. 3,475,716 shows a retainer consisting of a flexible strap, one end of which has an opening for passage of one connector and the other end is provided with a fastener formed of a flexible band having a closure to keep the other conductor in place after it has been connected to the first conductor. U.S. Pat. No. 3,183,470 discloses a locking device for two electric cords which maintains them in contact by means of a pair of U-shaped locking members. The device is provided with a padlock which may be opened only by authorized personnel having a key therefor. While these prior patents disclose the concept of an electric cord locking device having different forms of clamping elements, the device of this invention provides a new approach to the structure of locking devices which has certain advantages over the prior devices.
In view of the foregoing, it is the main object of this invention to provide an improved locking device which will maintain by positive action two electric cords connected together when subjected to a pulling force exerted thereon.
Another object of this invention is to provide a simple locking device which can readily and safely be installed by the user to prevent accidental separation of two electric cords without necessitating the use of any tools for installation thereof.
A further object of this invention is to provide a removable locking device for electric cords which can easily be manufactured at a low cost from commercially available materials.